10211 Heat Recovery

Energy in the fuel is released during combustion and converted to shaft work and heat. Shaft work drives the generator while heat is released from the engine through coolant, exhaust gas, and surface radiation. Approximately 60 to 70% of the total energy input is converted to heat that can be recovered from the engine exhaust and jacket coolant. Smaller amounts of heat are also available from the lube oil cooler and, if available, the turbocharger's intercooler and aftercooler. Steam or hot water can be generated from recovered heat that is typically used for space heating, reheat, domestic hot water, and absorption cooling.

By recovering heat from the jacket water and exhaust, approximately 70 to 80% of the fuel's energy can be effectively used. Heat in the engine jacket coolant accounts for up to 30% of the energy input and is capable of producing 200°F hot water. Some engines, such as those with high pressure or ebullient cooling systems, can operate with water jacket temperatures of up to 265°. Engine exhaust heat is 10 to 30% of the fuel input energy. Exhaust temperatures of 850 to 1200°F are typical. Only a portion of the exhaust heat can be recovered since exhaust gas temperatures are generally kept above condensation thresholds. Most heat recovery units are designed for a 300 to 350°F exhaust outlet temperature to avoid the corrosive effects of condensation in the exhaust piping. Exhaust heat can be used for thermal applications ranging from hot water to about 230°F or low-pressure steam (15 psig).

Solar Stirling Engine Basics Explained

Solar Stirling Engine Basics Explained

The solar Stirling engine is progressively becoming a viable alternative to solar panels for its higher efficiency. Stirling engines might be the best way to harvest the power provided by the sun. This is an easy-to-understand explanation of how Stirling engines work, the different types, and why they are more efficient than steam engines.

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